Temperature-responsive switch

ABSTRACT

A temperature-responsive fluid switch including a cylindrical valve chamber with a fluid inlet port for directing fluid generally radially into the chamber and opposed central outlet ports extending from the opposite ends of the chamber with a bimetallic disc extending across the chamber and selectively blocking the outlet ports to prevent fluid flow from the inlet port to one of the outlet ports while permitting flow to the other outlet port.

United States Patent [72] Inventors Harold L. Fox;

Ruel R. Clark, both of Salt Lake City, Utah [21 Appl. No. 752,034

[22] Filed Aug. 12, 1968 [45] Patented July 27, 1971 [73] Assignee l-T-EImperial Corporation [54] TEMPERATURE-RESPONSIVESWITCH 8 Claims, 4Drawing Figs.

[52] U.S,Cl. 137/457, 73/3635, 73/3783, [ZS/41.12, 123/41.l5 [51] lnt.C1,.Fl6k 25/00, 001k 3/00, FOlp 5/14 [50] Field ofselrch 73/3635.

378.3;236/5, 19,94, 48, 66; 137/457, 468, 469; l23/4l.l2,41.02, 180 T,108

[56] "References Cited UNITED STATES PATENTS 1,763,802 6/1930 Levy123/41 12/1937 Vaughn 297/8 2,301,318 11/1942 Peo 188/89 2,590,1113/1952 McCracken et a1. 158/363 2,742,927 4/1956 Frumet 137/4683,411,712 11/1968 O'Haraetal. 236/93 3,417,768 12/1968 Wasson 137/73Primary Examiner-Mark Newman Assistant Examiner-Ronald CoxAIt0rney-l-lofgren, Wegner, Allen, Stellman & McCordTEMPERATURE-RESPONSIVE SWITCH BACKGROUND OF THE INVENTION In the pasttemperature-responsive switching devices have been fairly complex intheir construction requiring a plurality of moving parts, springs, etc.A typical prior arrangement is shown in the Sparrow U.S. Pat. No.3,091,393 and the switch disclosed and described therein includes apivotally mounted valve member having valving surfaces at each endthereof selectively engageable with adjacent stationary valve seatswhich communicate with outlet ports. Fluid is supplied to a chamberadjacent the valve seats and depending upon the pivotal position ofthevalve member flows out the open one of the outlet ports. For biasing thevalve member and controlling the position thereof atemperature-responsive bellows is provided as well as a biasing spring.This is a complicated and costly arrangement.

SUMMARY OF THE PRESENT INVENTION In accordance. with the presentinvention a temperature responsive fluid switch is provided that has nomoving parts with the exception of a temperature responsive bimetallicmember. The switch has two outlet ports, one of which carries fluid whenthe surrounding temperature is below a predetermined value and the otherof which carries fluid when the surrounding temperature is above apredetermined value. This enables the switch to be employed in anassociated fluid circuit, such as a fluidic circuit, with either thepresence ofa fluid signal at one outlet port or the absence of a fluidsignal at the other outlet port indicating a high-temperature conditionsensed by the switch.

The device includes an annular valving chamber to which fluid is portedwith opposed aligned outlet ports extending from the annular chamber.The only moving part is a discshaped bimetallic member in the chamberwhich when the temperature is below a predetermined value engages andblocks flow from one of the ports and when the predetermined temperatureis exceeded snaps across the chamber engaging and blocking the otheroutlet port and at the same time opening the previously blocked port.

While this device is useful wherever temperature limiting is part of acontrol system, it is particularly useful in a system requiring fluidicenergizing signals. Such a circuit is a failsafe control circuit whereina plurality of these temperature sensing fluid switches are arranged inseries for sensing excessive temperatures at a plurality of locations ina circuit so that if the temperature of any one is exceeded the systemwill be shut down. Also provided in this circuit are visual indicatingdevices associated with each of the switches and responsive to a fluidsignal from one of the outlet ports of the associated switch forproviding a visual indication when an excessive temperature is sensed bythe switch.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view of atemperature responsive switch according to the present invention;

FIG. 2 is a cross section taken generally along line 22 of FIG. 1;

FIG. 3 is a cross section taken generally along line 3-3 of FIG. I; and

FIG. 4 is a schematic diagram of a failsafe control circuit utilizingthe switch shown in FIGS. 1 to 3.

While we have shown and shall hereinafter describe one embodiment of theinvention, it is to be understood that it is capable of manymodifications. Changes, therefore. in the construction and arrangementmay be made without departing from the spirit and scope of the inventionas defined in the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. I to3 a fluidic temperature responsive switch is seen to include a firstbody member 12 having a cylindrical central recess 13 therein. A secondcomplementary body member 15 has a central cylindrical projection 17received within the recess 13 and defining therewith a cylindrical valvechamber 18. The chamber 18 has a diameter at least six times its height.An inlet port 20 is defined by a drilled passage extending radiallythrough the body member 12 and into the body member 15. The inlet portthus has a first portion 23 communicating with the top end of thechamber 18 and a second portion 24 communicating with the bottom end ofthe chamber.

A suitable inlet fitting 26 is fixed within the body member 12 andcommunicates freely with inlet port 20. Fitting 26 is adapted to beconnected to a source of supply fluid, such as air, under pressure. Thebody members 12 and 15 are connected together by suitable threadedfasteners 28 with the parts being angularly aligned by an aligning pin30 as shown in FIG. 3.

Extending axially from the chamber 18 in the body member 12 is a lowtemperature outlet port 32 which is located centrally with respect tothe chamber 18. A radially extending outlet passage 34 communicates atone end with port 32 and at the other end with an outlet fitting 36.Extending centrally from the opposite end of the chamber 18 in the bodymember 15 is a high temperature outlet port 38. A radially extendingpassage coplanar with passage 34 is connected at one end to port 38 andat the other end communicates with an outlet fitting 42.

For the purpose of selectively blocking the ports 32 and 38 a bimetallicdisc 46 is provided in chamber 18. The disc 46 is circular inconfiguration with a central spherical portion 47. The disc 46 extendssubstantially diametrally across the chamber 18 and has a relaxed axiallength slightly greater than the height of the chamber 18 so that thecenter portion 50 of the disc tightly engages one of the ports as shownin FIGS. 2 and 3. As shown in the drawing, the disc is in its lowtemperature position with valving portion 50 blocking flow throughoutlet port 38. The disc is constructed so that when a predeterminedtemperature is exceeded it will snap from the position shown in FIG. 2to the position shown in FIG. 3 where the opposite center portion 52 ofthe disc engages the port 32 blocking any flow from that port.

Assuming that the fitting 26 is connected to a suitable source of fluidunder pressure and the temperature surrounding the device 10 is belowthe predetermined value at which disc 46 snaps, fluid will flow frominlet port 20, inlet portion 24 inside spherical portion 47 and out thelow temperature or cold" port 32. The fluid signal issuing from port 32may be utilized in associated circuitry to indicate that the temperatureof the component sensed by switch I0 is within predetermined permissiblelimits. When the temperature surrounding switch 10 rises above thepredetermined value disc 46 will snap opening port 38 and blocking port32 so that inlet fluid flows then from port 20, through port portion 23,within the inverted bimetallic disc 46, through port 38 and out fitting42. This signal may be used to indicate an excessive temperaturecondition associated with switch 10, or alternatively, the absence ofasignal from port 32 may be used to indicate an excessive temperaturecondition. It is important to note that the switch 10 may be used tosense either the surrounding temperature or the temperature ofthe fluidflowing in inlet 26.

In FIG. 4 a plurality of the switches are employed in a failsafe controlcircuit for a diesel engine. The circuit functions to close a fuel'valveand shut off fuel flow to the diesel engine when the temperature of anyone of the cylinders in the engine exceeds a predetermined criticalvalue. The engine fuel valve 70 remains open in response to the presenceofa fluid signal in line 71 and closes in response to the absence ofasignal in line 71 thereby shutting offthe flow of fuel to the engine.

There is one temperature switch 74, 75, 76, 77, 78, 79, 80 and 81associated with each of the eight cylinders in the diesel engine. Amechanical heat conducting connection is provided between each cylinderand the associated temperature switch so that the switch can sensecylinder temperature. Associated with each of the switches is a latchingvisual indicator 85, 86, 87, 88, 89, 90, 91 and 92 which provides avisual representation when the associated switch senses an excessivepressure. Each of the switches includes a manual reset 96. These visualindicators may be any one of a number of conventional visual indicatorsthat respond to fluid signals. The indicators are connected to thehigh-temperature outlets 38 of the temperature switches and respond to afluid signal in the high temperature outlet for providing a visualrepresentation indicating an excessive temperature. After being placedin a state representing an excessive temperature the switches must bemanually reset.

The low-temperature outlets 32 of each of the switches (except switch81) is connected through suitable conduits 97 with the inlet ports ofthe following switches. In this manner the switches are arranged inseries. The cold outlet port 32!: ofthe last switch 81 is connected topassage 71 providing a signal to maintain the engine fuel valve in itsopen position.

When the temperature of the cylinders associated with all of theswitches 74 to 81 is below the predetermined critical value, fluidflowing in inlet port 200 of the first switch 74 will flow out the coldoutput 32a to the inlet 20b of switch 75 and from switch 75 to the inletof switch 76, etc., through all of the following switches and out port32/: to switch 81 maintaining fuel valve 70 open. if the temperature ofany one of the cylinders exceeds the predetermined value the switchassociated with that cylinder will snap to its high temperature positionblocking flow from the 'cold outlet port and directing flow to its hotoutlet port. This interrupts the flow through the following temperatureswitches terminating flow through line 71 permitting the engine fuelvalve to move to its closed position cutting off the supply of fuel tothe engine and thereby shutting down the engine. For example, when theswitch 76 senses an excessive temperature in cylinder 3, cold port 320will be blocked interrupting flow to switch 77 and the followingswitches as well as to the engine fuel valve 70. At the same time switch76 will direct inlet flow through to outlet port 380 and the visualindicator 87 providing a visual indication that cylinder 3 is theoverheated cylinder. After the overheating problem has been corrected itis necessary to activate the manual reset associated with indicator 87to remove the excessive temperature representation.

it should be understood that while the present temperature switch isparticularly useful in the failsafe circuit shown in H6. 4 that thereare numerous other applications for the switch.

We claim:

1. A fluid temperature switch, comprising: body means having a fluidinlet port, means for supplying fluid to said fluid inlet port, firstoutlet port means in said body means, second outlet port means in saidbody means generally opposed and aligned with said first outlet portmeans, both of said outlet port means positioned to receive fluid fromsaid inlet port, and a temperature responsive bimetallic member forselectively blocking communication between the inlet port and either ofthe outlet port means, said bimetallic member being positioned so that acentral portion thereof engages said first outlet port and blockscommunication between the inlet port and the first outlet port means ina first temperature range and positioned so that a central portionthereof engages said second outlet port and blocks communication betweenthe inlet port and the second outlet port means in a second temperaturerange.

2. A fluid temperature switch as defined in claim 1, wherein saidbimetallic member is a disc having a generally spherical portion, saidspherical portion engaging both of said outlet port means to block flowtherein.

3. A fluid temperature switch as defined in claim 1, wherein said firstand second outlet port means are spaced and aligned,

said bimetallic member being positioned between said first and secondoutlet port means for selective engagement therewith.

4. A fluid temperature switch as defined in claim 1, wherein said bodymeans has a generally annular chamber therein, said inlet portcommunicating with said chamber and directing fluid generally radiallytherein, both said outlet port means extending axially from said chamberand communicating therewith, said outlet port means being locatedsubstantially centrally with respect to said chamber, said bimetallicmember being a generally circular disc in said chamber, and having aspherical portion adapted to project against said first port means insaid first temperature range and project against said second port meansin said second temperature range, said inlet port being positioned todirect fluid continuously to opposite sides of said bimetallic member.

5. A fluid temperature switch, comprising: a first body member having acylindrical recess therein, a second body member having a cylindricalprojection received in said recess and defining therewith a fluidchamber, a radially disposed inlet port in said first body membercommunicating with said chamber, said inlet port communicating with thechamber at the periphery of said recess and extending radially inwardlyfrom the periphery along the bottom of said recess, an inlet fittingprojecting from said first body member and communicating with said inletport, a first outlet port in said first member extending axially andcentrally from said recess, first outlet passage means in said firstmember extending radially from said first outlet port to the peripheryof said first body member, a second outlet port in said second bodymember extending axially and centrally from the end of said projectionadjacent the chamber, second outlet passage means in said second bodymember extending radially from said second port to the periphery of saidsecond body member, and a bimetallic disc mounted in said chamber andextending substantially diametrally across said chamber, said dischaving a central generally spherical portion, one side of said sphericalportion being engageable with said first port blocking flow thereto insaid first temperature range, the other side of said spherical portionbeing engageable with said second port blocking flow therethrough insaid second temperature range.

6. A subsystem for deactivating a system upon the occurrence ofexcessive temperature at any one of a plurality of locations in thesystem, comprising: means for terminating operation of the system, aplurality-of temperature sensing switches positioned to sensetemperature at a plurality of locations in the system, each of thetemperature-sensing switches including body means having a fluid inletport, means for supplying fluid to said fluid inlet port, first outletport means in said body means, second outlet port means in said bodymeans generally opposed to said first outlet port means, both of saidoutlet port means positioned to receive fluid from said inlet port, anda temperature responsive bimetallic member for selectively blockingcommunication between the inlet port and either of the outlet portmeans, said bimetallic member being positioned to block communicationbetween the inlet port and the first outlet port means in a firsttemperature range and positioned to block communication between theinlet port and the second outlet port means in a second temperaturerange, said second temperature range being the higher temperature range,means connecting the second port means of at least one temperatureswitch with the inlet port means of another temperature switch, one ofthe outlet port means of the latter temperature switch providing asignal to said system terminating means.

7. A subsystem for deactivating a system upon the occurrence ofexcessive temperature at any one of a plurality of locations in thesystem as defined in claim 6, including a fluid responsive visualindicating device associated with each temperature switch, the firstoutlet port means of each switch being connected to direct a fluidsignal to the associated indicator, the second outlet port means of atleast one switch being connected to direct a fluid signal to the nextport of the following switch.

prevent actuation of said system terminating means and when thetemperature of the locations associated with either of said switches isin the second temperature range fluid from one of the switches will flowfrom the associated first port means interrupting flow from theassociated second port means thereby actuating the system-terminatingmeans.

1. A fluid temperature switch, comprising: body means having a fluidinlet port, means for supplying fluid to said fluid inlet port, firstoutlet port means in said body means, second outlet port means in saidbody means generally opposed and aligned with said first outlet portmeans, both of said outlet port means positioned to receive fluid fromsaid inlet port, and a temperature responsive bimetallic member forselectively blocking communication between the inlet port and either ofthe outlet port means, said bimetallic member being positioned so that acentral portion thereof engages said first outlet port and blockscommunication between the inlet port and the first outlet port means ina first temperature range and positioned so that a central portionthereof engages said second outlet port and blocks communication betweenthe inlet port and the second outlet port means in a second temperaturerange.
 2. A fluid temperature switch as defined in claim 1, wherein saidbimetallic member is a disc having a generally spherical portion, saidspherical portion engaging both of said outlet port means to block flowtherein.
 3. A fluid temperature switch as defined in claim 1, whereinsaid first and second outlet port means are spaced and aligned, saidbimetallic member being positioned between said first and second outletport means for selective engagement therewith.
 4. A fluid temperatureswitch as defined in claim 1, wherein said body means has a generallyannular chamber therein, said inlet port communicating with said chamberand directing fluid generally radially therein, both said outlet portmeans extending axially from said chamber and communicating therewith,said outlet port means being located substantially centrally withrespect to said chamber, said bimetallic member being a generallycircular disc in said chamber, and having a spherical portion adapted toproject against said first port means in said first temperature rangeand project against said second port means in said second temperaturerange, said inlet port being positioned to direct fluid continuously toopposite sides of said bimetallic member.
 5. A fluid temperature switch,comprising: a first body member having a cylindrical recess therein, asecond body member having a cylindrical projection received in saidrecess and defining therewith a fluid chamber, a radially disposed inletport in said first body member communicating with said chamber, saidinlet port communicating with the chamber at the periphery of saidrecess and extending radially inwardly from the periphery along thebottom of said recess, an inlet fitting projecting from said first bodymember and communicating with said inlet port, a first outlet port insaid first member extending axially and centrally from said recess,first outlet passage means in said first member extending radially fromsaid first outlet port to the periphery of said first body member, asecond outlet port in said second body member extending axially andcentrally from the end of said projection adjacent the chamber, secondoutlet passage means in said second body member extending radially fromsaid second port to the periphery of said second body member, and abimetallic disc mounted in said chamber and extending substantiallydiametrally across said chamber, said disc having a central generallyspherical portion, one side of said spherical portion being engageablewith said first port blocking flow thereto in said first temperaturerange, the other side of said spherical portion being engageable withsaid second port blocking flow therethrough in said second temperaturerange.
 6. A subsystem for deactivating a system upon the occurrence ofexcessive temperature at any one of a plurality of locations in thesystem, comprising: means for terminating operation of the system, aplurality of temperature sensing switches positioned to sensetemperature at a plurality of locations in the system, each of thetemperature-sensing switches Including body means having a fluid inletport, means for supplying fluid to said fluid inlet port, first outletport means in said body means, second outlet port means in said bodymeans generally opposed to said first outlet port means, both of saidoutlet port means positioned to receive fluid from said inlet port, anda temperature responsive bimetallic member for selectively blockingcommunication between the inlet port and either of the outlet portmeans, said bimetallic member being positioned to block communicationbetween the inlet port and the first outlet port means in a firsttemperature range and positioned to block communication between theinlet port and the second outlet port means in a second temperaturerange, said second temperature range being the higher temperature range,means connecting the second port means of at least one temperatureswitch with the inlet port means of another temperature switch, one ofthe outlet port means of the latter temperature switch providing asignal to said system terminating means.
 7. A subsystem for deactivatinga system upon the occurrence of excessive temperature at any one of aplurality of locations in the system as defined in claim 6, including afluid responsive visual indicating device associated with eachtemperature switch, the first outlet port means of each switch beingconnected to direct a fluid signal to the associated indicator, thesecond outlet port means of at least one switch being connected todirect a fluid signal to the next port of the following switch.
 8. Asubsystem for deactivating a system upon the occurrence of excessivetemperature at any one of a plurality of locations in the system asdefined in claim 7, wherein the one of the outlet port means of saidlatter switch connected to said system terminating means is the secondoutlet port means whereby when the temperature of the locationsassociated with each of said switches is in the first lower range, fluidwill flow from the second port means of both the switches and preventactuation of said system terminating means and when the temperature ofthe locations associated with either of said switches is in the secondtemperature range fluid from one of the switches will flow from theassociated first port means interrupting flow from the associated secondport means thereby actuating the system-terminating means.